The Role of Soil in Plant Nutrition

Question 1

True or False?

The conversion of plant-available forms of nitrogen into microbial or plant biomass is an example of mineralization.

Answer 1

False

Question 2

True or False?

In soil with a very low cation exchange capacity, the most efficient approach to using potassium fertilizer would be to apply frequent small doses rather than a single large dose.

Answer 2

True

Question 3

True or False?

Potassium is more readily leached from a neutral sandy soil than from an acid clayey soil.

Answer 3

True

Question 4

Compared to the same soil used for cropland, a forested soil would be expected to lose ________ total P to streams draining the watershed.

less, more, same amount of

Answer 4

less

Question 5

Methemoglobinemia is principally a potential threat to ________.

A. babies drinking water high in sulfate
B. babies drinking water high in nitrate
C. adults drinking water high in sulfate
D. adults drinking water high in nitrate
E. all of the above

Answer 5

B. babies drinking water high in nitrate

Question 6

Nitrogen is a component of which essential plant compounds?

Select one:
A. chlorophyll
B. proteins
C. enzymes
D. DNA
E. all of the above

Answer 6

E. all of the above

Question 7

True or False:

Most micronutrients play essential roles in plant metabolism as enzyme activators.

Answer 7

True

Question 8

In order for nitrate to form from soil organic matter, ________ must be present in the soil.

A. Nitrobacter
B. Nitrosomonas
C. either A or B
D. both A and B
E. none of the above

Answer 8

D. both A and B

Question 9

The total phosphorus lost from various watersheds is most closely correlated with ________.

A. high soil permeability
B. high soil erosion
C. high percentage of forested land
D. low soil CEC
E. extent of artificial drainage

Answer 9

B. high soil erosion

Question 10

In what range of soil pH is phosphorus generally most available to plants?

A. 3.5-4.5
B. 7.0-8.0
C. 5.5-7.0
D. 4.5-5.5
E. >8.0

Answer 10

C. 5.5-7.0

Question 11

Which of the following nutrient elements is usually present in the soil solution as a simple cation?

Select one:
A. Cl
B. Mo
C. Zn
D. B
E. all of the above

Answer 11

C. Zn

Question 12

True or False:

Ammonia volatilization is a process by which much-needed nitrogen is added to the pool of plant-available nitrogen in soils.

Answer 12

False

Question 13

The nutrient most often limiting the growth of aquatic plants and algae in unpolluted freshwater lakes is ________.

Select one:
A. P
B. S
C. K
D. N
E. none of the above

Answer 13

A. P

Question 14

True or False?

The ammonium form of N readily leaches from NC soils

Answer 14

True

Question 15

True or False:

Micronutrient deficiencies are more likely to occur where inorganic chemical fertilizers, rather than organic manures, have been used to stimulate vigorous plant growth.

Answer 15

True

Question 16

True or False:

Nitrogen use efficiency is consistent among all plants and averages about 95%.

Answer 16

False

Question 17

In acid soils, the principal chemical form of potassium available for plant uptake is ________.

Select one:
A. K+
B. H2KO2-
C. HKO22-
D. K2O
E. P-

Answer 17

A. K+

Question 18

Wetlands and forests growing along the banks of rivers remove much nitrogen from groundwater by the process of ________.

A. nitrification
B. ammonification
C. immobilization
D. denitrification
E. none of the above

Answer 18

Denitrification

Question 19

True or False:

Denitrification is the aerobic process by which wetlands remove nitrogen from groundwater.

Answer 19

False

Question 20

Because of ________, soils developed in marine marshes can become extremely acidic if drained for agriculture or used as topsoil.

A. reduction of sulfates
B. oxidation of sulfates
C. oxidation of sulfides
D. reduction of elemental sulfur
E. all of the above

Answer 20

C. oxidation of sulfides

Question 21

Applied to crops, the term lodging refers to ________.

A. short, stubby plants starving for N or S
B. plants losing their leaves because of an N imbalance
C. plants falling over, often as a result of too much N
D. infestation with a high number of insect larvae lodged in the fruits or seeds
E. pre-mature fruit drop as a result of N deficiency

Answer 21

C. plants falling over, often as a result of too much N

Question 22

True or False:

The sulfur dioxide in the atmosphere resulting from fossil fuel burning, volcanoes, and forest fires can be an important source of sulfur nutrition for plants.

Answer 22

True

Question 23

True or False:

Most nitrogen leaching to groundwater is in the form of ammonium.

Answer 23

False

Question 24

True or False:

The natural microbial oxidation of nitrogen released by organic matter mineralization is a source of soil acidity.

Answer 24

True

Question 25

In various parts of the world, soil phosphorus is associated with which of the following environmental problems?

A. eutrophication of lakes because of a build-up of soil P in the watersheds
B. soil degradation because of the depletion of soil phosphorus
C. toxic levels of phosphate in groundwater supplies
D. both A and B
E. all of the above

Answer 25

D. both A and B

Question 26

True or False:

Soil phosphorus is associated with the eutrophication of lakes.

Answer 26

True

Question 27

To be practical, a nitrification inhibitor should kill or inhibit ________.

A. Nitrosomonas
B. Nitrobacter
C. either A or B
D. none of the above

Answer 27

A. Nitrosomonas

Question 28

True or False:

Most nitrogen leaching to groundwater is in the form of nitrate.

Answer 28

True

Question 29

Mycorrhizae improve the nutrition of many plants by ________.

A. transporting phosphorus through the soil to the plant root
B. fixing atmospheric phosphorus into forms readily used by plants
C. readily dissolving iron and aluminum phosphate compounds
D. making the root cell membrane more permeable to phosphate ions
E. masking P-fixation sites on the surface of certain soil minerals

Answer 29

A. transporting phosphorus through the soil to the plant root

Question 30

True or False:

Some nitrogen-containing fertilizers are significant sources of soil acidity in cultivated soils.

Answer 30

True